1. Field of Invention
This invention relates to a semiconductor process, and more particularly relates to a method for fabricating a metal-oxide-semiconductor (MOS) device.
2. Description of Related Art
MOS is a basic structure widely applied to various semiconductor devices, such as memory devices, image sensors and display devices.
The traditional MOS transistor is difficult to scale down due to the limitation of the fabricating process, so multi-gate transistors with better properties are developed. One example is the fin field-effect transistor (FinFET), which has a 3D gate structure to enhance the control on the channel and inhibit the leakage caused by the punch-through effect, and hence has a higher gate control ability than the conventional MOS transistor.
However, in current FinFET process, the implant angle of the implant process for forming the source/drain (S/D) extension regions and the halo regions is much limited, so the process margin is very small. Moreover, the S/D extension and the halo regions thus formed are uneven in dopant concentration and depth, and even cause leakage.